Therapeutic light source and method

ABSTRACT

A therapeutic light source, for example for photodynamic therapy (PDT), comprises an air-cooled array of LED&#39;s (L x,y ), the air being vented in the vicinity of the array. The array may be mounted at the distal end of a hand piece suitable for invasive therapy. The LED&#39;s may be coupled to a light guide (W, L). The emission spectra of the LED&#39;s may be substantially limited to the range 550 to 660 nm, and preferably to one of the ranges 590 to 640 nm, 560 to 644 nm, 650 to 660 nm, and 550 to 570 nm. The therapeutic light source may comprise a non-planar array of light-emitting diodes L conforming with the shape of an external area to be treated or diagnosed. The therapeutic light source may comprise a non-planar array of independently switchable red and blue light-emitting diodes L R , L B , mounted on a flexible backing.

[0001] The present invention relates to a non-coherent light source foruse in therapy such as photodynamic therapy (PDT), particularly usinglight emitting diodes (LED's).

[0002] Photodynamic therapy involves the administration of aphotosensitising drug to an affected area, and its subsequentirradiation with light—see for example ‘The Physics of PhotodynamicTherapy’ by B C Wilson and M S Patterson, Physics in Medicine & Biology31 (1986) April No. 4, London GB.

[0003] The document GB 2,212,010 discloses a therapeutic light sourcewhich uses an array of discrete LED's as an alternative to lasers orlaser diodes. The output of the LED's is focussed so as to provide thenecessary intensity.

[0004] The document WO 94/15666 discloses a therapeutic light sourcespecifically for PDT, with an integrated array of LED's mounted on thedistal end of a hand piece. The LED's are overdriven to give thenecessary intensity, and cooled by the flow of water around a closedloop passing along the hand piece. The document U.S. Pat. No. 5,728,090discloses a somewhat similar device with various different types of headcontaining integrated LED matrices. These devices require complicatedliquid cooling circuits which would add to the cost of the device andadd to the bulk of the hand piece, which is disadvantageous for invasiveuse.

[0005] The document U.S. Pat. No. 5,728,090 mentions that the wavelengthof the LED's is between 300 nm and 1300 nm and is selected based uponthe particular photosensitive dye used during PDT. However, thewavelengths of LED's capable of providing the necessary intensity forPDT cannot freely be chosen within that range.

[0006] According to one aspect of the present invention, there isprovided a light source for therapy and/or diagnosis, comprising anon-planar array of light-emitting diodes conforming with the shape ofan external area to be treated or diagnosed.

[0007] According to another aspect of the present invention, there isprovided a light source for therapy and/or diagnosis, comprising a firstarray of light-emitting diodes and a second array of light emittingdiodes movably connected thereto.

[0008] According to another aspect of the present invention, there isprovided a light source for therapy and/or diagnosis, comprising anarray of light-emitting diodes mounted on the curved inner surface of ahousing arranged to cover at least part of the length of a patient.

[0009] According to another aspect of the present invention, there isprovided a light source for therapy or diagnosis of a patient,comprising an array of light-emitting diodes arranged within a housing,and an aperture allowing a part of the patient's body to be insertedinto the housing, the array being arranged to direct light onto the partof the patient's body when inserted into the housing.

[0010] According to another aspect of the present invention, there isprovided a light source for therapy or diagnosis of a patient,comprising an array of light-emitting diodes arranged within a sleeve soas to direct light onto part of an arm and/or hand of a patient wheninserted into the sleeve.

[0011] According to another aspect of the present invention, there isprovided a light source for therapy or diagnosis of a patient,comprising an intraluminal probe carrying on the surface thereof anarray of discrete light-emitting diodes.

[0012] According to another aspect of the present invention, there isprovided a therapeutic light source comprising an air-cooled array ofLED's, the air being vented in the vicinity of the array. In oneembodiment, the array is mounted at the distal end of a hand piecesuitable for invasive therapy.

[0013] According to another aspect of the present invention, there isprovided a therapeutic light source comprising an array of LED's coupledto a light guide for delivering the light to the area to be treated.Preferably, the LED's are directly coupled without intervening opticaldevices.

[0014] According to another aspect of the present invention, there isprovided a therapeutic light source comprising an array of LED's withemission spectra substantially limited to the range 550 to 660 nm, andpreferably to one of the ranges 590 to 640 nm, 560 to 644 nm, 650 to 660nm, and 550 to 570 nm.

[0015] According to another aspect of the present invention, there isprovided a therapeutic light source comprising an array of LED's withpeak emission spectra of approximately 430 nm, 470 nm, 505 nm or 525 nm.

[0016] Specific embodiments of the present invention will now bedescribed with reference to the accompanying drawings, in which:

[0017]FIG. 1 is a diagram of a parallel-series matrix of discrete LED'sused in first and second embodiments of the present invention;

[0018]FIG. 2 is perspective diagram of the first embodiment;

[0019]FIG. 3 is a cross section of part of the first embodiment;

[0020]FIG. 4 is a graph showing the variation of intensity in across-section of the output of the first embodiment;

[0021]FIG. 5 is a cross-sectional diagram of a second embodiment;

[0022]FIG. 6 is a cross-sectional diagram of a third embodiment;

[0023]FIG. 7 is a cross-sectional diagram of a fourth embodiment;

[0024]FIG. 8 is a cross-sectional diagram of a fifth embodiment;

[0025]FIG. 9 is a graph showing the absorption spectrum of PpIX and theemission spectra of two examples of LED's suitable for use with theembodiments;

[0026]FIGS. 10a and 10 b are side and front views respectively of an LEDarray in a sixth embodiment for treatment of the face;

[0027]FIGS. 11a, 11 b and 11 c are a cross-section in the plane of thepatient's arm, a top view and a vertical cross-section transverse to thepatient's arm of an LED array in a seventh embodiment for treatment ofthe elbows of a patient;

[0028]FIG. 12 is a side view of an LED array in an eighth embodimentused for treatment of the foot or feet;

[0029]FIG. 13 is a side view of an LED array in a ninth embodiment usedfor treatment of the lower leg;

[0030]FIGS. 14 and 15 show arrangements of an LED array in tenth andeleventh embodiments for treatment of respectively the face and asection of a patient lying on a bed;

[0031]FIGS. 16a and 16 b show respectively front and side views of a setof similar LED arrays in an twelfth embodiment for treatment of one sideof a patient;

[0032]FIGS. 17a and 17 b show respectively front and side views of anLED array in a thirteenth embodiment for treatment of a section of oneside of a patient;

[0033]FIGS. 18a and 18 b are respectively side and end views of a set ofsimilar LED arrays in a fourteenth embodiment, for treatment of one sideof a patient lying down;

[0034]FIGS. 19a and 19 b are respectively side and end views of an LEDarray in a fifteenth embodiment for treatment of a section of a patientlying down;

[0035]FIGS. 20a and 20 b are top and side views respectively of anarrangement of LED arrays in a sixteenth embodiment for treatment of theface and/or scalp;

[0036]FIG. 21 shows a similar arrangement to that of FIGS. 20a and 20 b,in a seventeenth embodiment for treatment of the face and/or scalp of apatient lying down;

[0037]FIGS. 22a, 22 b and 22 c show respectively a side view, atransverse cross-section and a longitudinal cross-section of an LEDarray arranged within a sleeve in a eighteenth embodiment, for treatmentof the hand, forearm and/or elbow;

[0038]FIGS. 23a, 23 b and 23 c show respectively two different shapes offlexible LED array, and a flexible array applied as a patch onto theskin of a patient, in an nineteenth embodiment;

[0039]FIG. 24 shows an LED array arranged on the side of a cylindricalintraluminal probe in a twentieth embodiment;

[0040]FIG. 25 shows an LED array arranged on the surface of a sphericalintraluminal probe in a twenty-first embodiment; and

[0041]FIG. 26 shows a more specific example of the flexible LED array inthe nineteenth embodiment.

[0042] In a therapeutic light source in the first embodiment, asillustrated in FIGS. 1 to 5, light is emitted from a parallel-seriesmatrix of LED's L connected through a current-limiting resistor R to asource of a voltage+V. The LED matrix is mounted on a heatsink array Hparallel to and spaced apart from a fan array F by support rods R. Airis blown by the fan array F onto the back of the heatsink array H.

[0043] As shown in more detail in FIG. 3, the heatsink array H comprisesa plurality of individual heatsinks h mounted on the ends of the legs ofthe LED's, which pass through a support plate P. Each leg is soldered toan adjacent leg of another of the LED's in the same column. The supportplate P is perforated to allow air to flow more freely around theheatsinks h and the LED's L.

[0044] The LED's L are arranged so as to produce a substantially uniformillumination of±10% or less across a treatment field by selecting thebeam divergence and spacing of the LED's L so that their individualbeams overlap without causing substantial peaks or troughs in intensity.In the example shown in FIG. 4, uniformity of±6% is achieved. In thisembodiment, no optical system is needed between the LED's and thepatient; instead, the light is emitted directly from the LED's onto thepatient. As the light is not concentrated by any optical system, theLED's have individual power outputs of at least 5 mW and preferably atleast 10 mW, to give the necessary fluence rates in the treatment fieldof at least 30 mW/cm² in the red region of the spectrum and at least 10mW/cm² in the blue region.

[0045] In one specific example, a 15 cm diameter array of 288 ‘Superflux’ LED's was used to produce a total light output of 8 W at 45 mW/cm²in the treatment field. The LED's were driven at a higher current loadthan their specification while being cooled by forced air convectionfrom the fans F. In the specific example, the current was limited to 90mA per column of diodes, but may be increased to 120 mA or more ifincreased light output is needed. The number of diodes in series, ineach column, is selected so that the total forward operating voltage isas close as possible to, but less than, the power supply output voltage,in this case 48 V. This arrangement avoids wasteful in-circuit heatingand maximizes the operating efficiency of the electrical system.

[0046] A method of treatment for oncological and non-oncological skindiseases such as cases of actinic/solar keratoses, Bowen's disease,superficial basal cell carcinoma, squamous cell carcinoma,intraepithelial carcinoma, mycosis fungoides, T-cell lymphoma, acne andseborrhoea, eczema, psoriasis, nevus sebaceous, gastrointestinalconditions (e.g. Barratt's oesophagus and colorectal carcinomas),gynaecological disorders (e.g. VIN, CIN and excessive uterine bleeding),oral cancers (e.g. pre-malignant or dyplastic lesions and squamous cellcarcinomas), viral infections such as herpes simplex, molluscumcontagiosum, and warts (recalcitrant, verruca vulgaris or verrucaplantaris), alopecia areata, or hirsutism, using the first embodiment,will now be described. A cream or solution containing a photosensitisingdrug such as 5-ALA is applied topically under medical supervision to theaffected area of the skin of the patient, or administered intravenouslyor orally. In another method of application for large areas, the patientmay be immersed in a bath of solution. The affected area may then becovered for a period of 3 to 6 hours, or up to 24 hours if the treatmentis to be continued the next day, to prevent removal of the drug andcarrier, or activation by sunlight. The area is then uncovered andexposed to light from the lamp according to the first embodiment for aperiod of 15 to 30 minutes. The treatment may then be repeated asnecessary, for a total of 1 to 3 treatments. This method is particularlysuitable for the treatment of patients with very large lesions ormultiple lesions extending over a large area.

[0047] In a method of treatment using the device of the firstembodiment, the LED array is positioned approximately parallel to anexternal affected area of a patient to be treated, with a separationsufficient to achieve the uniform illumination as shown in FIG. 4, forexample 2 to 5 cm. The device may also be used for cosmetic or partiallycosmetic treatment with a photosensitizing drug for portwine stainremoval and hair restoration/removal, and without a photosensitizingdrug for skin rejuvenation, wrinkle removal or biostimulation (includingwound healing).

[0048] The lamp may also be used for fluorescence detection(photodiagnosis).

[0049] The first embodiment may be modified in a second embodiment, asshown in FIG. 5, by the addition of a frusto-conical waveguide W, forexample of acrylic (e.g. Perspex™) or glass, supported by the supportrods R, which are extended in this embodiment. The waveguide W isarranged to concentrate light emitted by the LED's onto a smaller areawith higher intensity. This arrangement is suitable for treating smallerexternal surfaces.

[0050] The second embodiment may be modified in a third embodiment, asshown in FIG. 6, to deliver the light from the waveguide W into alightguide L for internal treatment. The lightguide L, such as anoptical fibre or fibre bundle, or liquid light guide, is held in alightguide receptacle or adapter A, that is compatible for example withOlympus, Storz, ACMI or Wolf light cable fittings, in abutment orimmediately adjacent relation with the narrow end of the waveguide W.The lightguide L may be of 3, 5 or 8 mm diameter. The support rods Ralign the optical axes of the waveguide W and lightguide L, so that thelight emitted by the waveguide W is launched into the lightguide L. Inthe third embodiment, the light is concentrated by the waveguide andemitted over a small area at the distal end of the lightguide L whichmay be inserted into body cavities for oral, gynaecological,gastrointestinal or intraluminal treatment.

[0051] The third embodiment may be modified in a fourth embodiment, asshown in FIG. 7, in which the discrete LED array is replaced by anintegrated multi-die LED matrix IM (for example part no. OD 6380, OD6624 or OD 6680 available from AMS Optotech, Bristol, UK) mounted on thesupport plate/heatsink P, H. A Peltier effect thermoelectric cooler PCis mounted in thermal contact with the opposite side of the supportplate P, the heated side of which is cooled by the fan F. The proximalend of the lightguide L is directly adjacent or abutting the integratedLED matrix IM, which are of similar cross-section so that the waveguideis not needed to launch the emitted light into the lightguide L.

[0052] A fifth embodiment, as shown in FIG. 8, is designed specificallyfor treatment of the cervix, such as PDT treatment. The fifth embodimenthas the form of a hand piece having a hollow stem S, for example ofacrylic or polycarbonate, through which air is blown at low pressure bya fan F mounted at the proximal end. The distal end has a head portionHP comprising a housing within which is mounted a discrete LED arraymounted on a support plate/heatsink P/H. Air passes through the hollowstem S onto the heatsink H so as to extract heat therefrom and is thenvented through apertures AP on the proximal side of the housing. Thedistal end of the housing is concave and dimensioned so as to fitclosely over the end of the cervix C. A transparent end window W, forexample of acrylic or glass, prevents infiltration of the LED's. Poweris carried to the LED's through wires (not shown) mounted on the wall ofthe acrylic stem S. In use, the hand piece is positioned so that thedistal end fits over the cervix of the patient and is clamped inposition for the duration of the treatment.

[0053] The selection of appropriate discrete LED's for PDT using any ofthe first to fourth embodiments will now be described, grouped accordingto die material.

[0054] A first suitable type of LED is based on aluminium indium galliumphosphide/gallium phosphide (AlInGaP/GaP) of transparent substrate (TS)or absorbing substrate (AS) type. The output wavelengths are in therange 590 to 640 nm with peak emission wavelengths of 590, 596, 605,615, 626, 630 and 640 nm. Commercially available examples are the‘SunPower’™ or ‘Precision Optical Power’™ series from Hewlett PackardCompany, designed for use in the automotive industry, for commercialoutdoor advertising and traffic management. Suitable LED's are thosepackaged as: SMT (surface mount technology) e.g. HSMA, HSMB, HSMC, HSMLseries and preferably HSMB HR00 R1T20 or HSMB HA00R1T2H; Axial e.g. HLMAor HLMT series; T1 e.g. HLMP series, preferably HLMP NG05, HLMP NG07,HLMP J105; T13/4 e.g. HLMP series, preferably HLMP DG08, HLMP DG15, HLMPGG08, HLMP DD16; Superflux™ e.g. HPWA or HPWT series, preferably HPWA(MH/DH/ML/DL) 00 00000, HPWT (RD/MD/DD/BD/RH/MH/DH/BH/RL/ML/DL/BL) 0000000, most preferably HPWT (DD/DH/DL/MH/ML/MD) 00 00000; SnapLED™ e.g.HPWT, HPWS, HPWL series, preferably HPWT (SH/PH/SL/PL) 00, HPWT(TH/FH/TL/FL) 00 or HPWS (TH/FH/TL/FL) 00. Suitable products from othermanufacturers include: of SMT type, Advanced Products Inc. (API) partno. HCL4205AO; of T1 type, American Bright Optoelectronics (ABO) partno. BL BJ3331E or BL BJ2331E; of Superflux type, ABO part no.'s BLF2J23, BL F2J33 and BL F1F33.

[0055] A second suitable type of LED is the aluminium indium galliumphosphide/gallium arsenic (AlInGaP/GaAs) type, with emission wavelengthsin the range 560 to 644 nm and peak emission wavelengths of 562 nm, 574nm, 590 nm, 612 nm, 620 nm, 623 nm and 644 nm. Examples commerciallyavailable from Toshiba in T1 package are the TLRH, TLRE, TLSH, TLOH orTLYH series, preferably TLRH 262, TLRH 160, TLRE 160, TLSH 1100, TLOH1100, TLYH 1100 or S4F4 2Q1; or in T13/4 package are the TLRH or TLSHseries, preferably TLRH 180P or TLSH 180P. Another example is KingbrightL934SURC-E.

[0056] A third suitable type of LED is aluminium gallium arsenic type(AlGaAs), with emission wavelengths in the range 650 to 660 nm. Examplesin T1 package include the Toshiba TLRA series, preferably TLRA 290P orTLRA 293P, and Kingbright L934 SRCG, L934 SRCH, and L934 SRCJ and inT13/4 package include Kingbright L53 SRCE.

[0057] A fourth suitable type of LED is gallium phosphide (GaP) type,with emission wavelengths in the range 550 to 570 nm.

[0058] A fifth suitable type of LED is indium gallium nitride (InGaN).In the type with an emission wavelength of 525 nm, commerciallyavailable examples include: in SMT package, API's HCL 1513AG; and in T1package, Famell's #942 467, Radio Spare's #228 1879 and #249 8752, API'sHB3h 443AG and Plus Opto's NSPG500S. In the type with emissionwavelengths of 470 and 505 nm and T1 package type, examples areFarnell's #142 773, Radio Spare's #235 9900 and American BrightOptoelectronics Inc.'s BL BH3PW1.

[0059] A sixth suitable type of LED is gallium nitride/silicon (GaN/Si),with an emission wavelength of 430 nm. One commercial example is SiemensLB3336 (also known as RS #284 1386).

[0060] Each of the above LED types is selected to have an emissionspectrum substantially coincident with the absorption spectrum of one ormore of the following common photosensitizers given below in Table 1,and therefore embodiments having such LED's are suitable for PDT. Forexample, FIG. 9 shows the absorption spectrum of PpIX, including peaksat 505 nm, 545 nm, 580 nm and 633 nm. Inset are the emission spectra, inunits of peak intensity and on the same wavelength axis, of LED part no.HPWA DL00 with a peak at 590 nm and LED part no. HPWT DH00 with a peakat 630 nm, the peaks having sufficient breadth to give a substantialoverlap with the 580 nm and 633 nm peaks respectively in the absorptionspectrum of PpIX. TABLE 1 Red absorption Red Peak Blue/GreenPhotosensitizer Band (nm) (nm) Peak (nm) Naphthalocyanines 780-810Chalcogenopyrilium dyes 780-820 Phthalocyanines (e.g. ZnII Pc) 670-720690 Tin etiopurpurin (SnET₂) 660-710 660-665 447 Chlorins (e.g.N-Aspartyl chlorin 660-700 664 e6 or NPe6) Benzoporphyrin derivative(BPD) 685/690 456 Lutetium texaphrin (Lu-Tex) 735 Al(S₁/S₂/S₃/S₄) Pc660-710 670/685 410, 480 Photofrin 625/630 405 Protoporphyrin IX(PpIX) - from 635 410, 505, 5/δAminolaevulinic Acid (5ALA) 540, 580Tetra m-hydroxyphenyl Chlorin 650 440, 525 (mTHPC)

[0061] The discrete LED array may comprise more than one different typeof LED, each with different emission spectra, selected to matchdifferent absorption bands of the selected photosensitizer. Each type ofLED may be switched independently. The penetration depth (i.e. the depthat which the intensity has been attenuated to e⁻¹) may also be varied byswitching on only one type of LED in the array so as to select asuitable emission band, since the penetration depth is a function of thewavelength.

[0062] The LED array may be composed of individually switchablespatially distinct segments of LED's. Selected segments may be switchedon so as to treat a selected area of the patient within the overall areaof the matrix array.

[0063] The lamp may include an electro-optical detector arranged tomonitor the light dose delivered and to switch off the light emissionwhen a target dose is reached. Alternatively, or additionally, thedetector is arranged to monitor the instantaneous light intensity and tovary the electrical power supplied to the tubes so as to maintain theintensity within predetermined limits, and/or to switch off the lightemission if a maximum limit is exceeded.

[0064] Various different arrangements of LED array suitable fortreatment of different areas of a patient will now be described. TheLED's are discrete LED's as described above. Except where statedotherwise, the LED's may be fan-cooled using integrated fans.

[0065]FIGS. 10a and 10 b show an array of LED's L in a sixth embodiment,arranged on a support P shaped as a curved visor for treatment of theface of a patient. The array is supported in front of the patient's faceby a head band HB or other head wear worn by the patient.

[0066]FIGS. 11a to 11 c show an array of LED's L in a seventh embodimentarranged within a cuboid housing HO which has two similar apertures APon one face, to allow the elbows to be inserted into the housing HO. Theedges of the apertures AP are cushioned to allow the arms to be restedcomfortably. Within the housing HO is arranged a surface SU which iscurved both in the plane of the arms and perpendicular to that plane, asshown in FIG. 11c. The LED's L are mounted on this surface SU so thatlight emitted therefrom is concentrated onto the elbows of the patient.

[0067]FIG. 12 shows an LED array L in an eighth embodiment mounted on asupport plate P, and covered by a transparent or translucent cover onwhich the foot or feet of the patient rest during treatment.

[0068]FIG. 13 shows an LED array L in a ninth embodiment mounted on asupport plate P and arranged for treatment of the lower leg of apatient.

[0069]FIGS. 14 and 15 show an LED array L, mounted in a housing HO inthe form of a trapezoid prism, the upper inner surface carrying the LEDarray and the lower surface being open to allow light to fall onto thepatient. The side faces may be reflective, or carry additional LEDarrays. In the tenth embodiment shown in FIG. 14, the housing HO ismounted at one end of a bed so that its height above the bed isadjustable, for facial treatment of a patient lying on the bed. In theeleventh embodiment shown in FIG. 15, the housing HO is mounted on astand ST and is adjustable in height, for treatment of a selected partof a patient lying on the bed.

[0070]FIGS. 16a and 16 b show a series of four coplanar LED arrays L ina twelfth embodiment arranged to treat one side of a patient. Each ofthe arrays is independently switchable so that selected sections of thepatient can be treated.

[0071]FIGS. 17a and 17 b show a single LED array L in a thirteenthembodiment positioned to treat a section of the patient.

[0072]FIGS. 18a and 18 b show a series of three coplanar LED arrays L ina fourteenth embodiment arranged to treat one side of a patient lyingdown. Each of the arrays is independently switchable so that selectedsections of the patient can be treated.

[0073]FIGS. 19a and 19 b show an array of LED's L in a fifteenthembodiment mounted on the inner surface of a curved housing HO fortreatment of a patient lying on a further, planar array of LED's, fortreatment of a section of the patient from all sides. The housing HO isslidable along the length of the patient so as to treat a selected areaof the patient. Sections of the planar array of LED's are switchable soas to illuminate only the selected section.

[0074]FIGS. 20a and 20 b show a sixteenth embodiment comprising afront-facial LED array L_(F) for directing light onto the face of thepatient from the front, a scalp LED array L_(s) and left and rightside-facial LED arrays L_(L), L_(R) moveably connected, for example byhinges, to the front-facial array L_(F), for directing light onto thescalp, left side of the face and right side of the face respectively.The front-facial array L_(F) is slideably attached to a stand ST forvertical adjustment to the head height of the patient, preferably whensitting.

[0075]FIG. 21 shows a seventeenth embodiment, similar to that of FIGS.20a and 20 b, except that it is arranged for facial and/or scalptreatment of a patient when lying down. The stand ST is mounted on abed, instead of being free-standing, and the arrays are rotated by 90°so as to correspond to the position of the patient's head when lyingdown.

[0076]FIGS. 22a, 22 b and 22 c show an eighteenth embodiment in which anLED array L is mounted on the inner surface of a sleeve SL so as todirect light onto the hand, forearm and/or elbow within the sleeve.

[0077]FIGS. 23a and 23 b show respectively a square and a rectangularLED array L in a nineteenth embodiment mounted on a flexible backingmember FB which can be applied to an area of the patient to be treated,such as part of the forearm as shown in FIG. 23c, with the LED's facinginwardly. The LED array thereby follows the contours of the area to betreated. The flexible backing member FB may be cooled by a fan which iseither discrete or connected thereto by a flexible membrane which isfixed around the flexible backing member FB and directs air from a fanonto the backing member, through which the air is vented.

[0078]FIG. 24 shows an LED array in a twentieth embodiment arranged onthe surface of a cylindrical intraluminal probe, while FIG. 25 shows anLED array in a twenty-first embodiment arranged on the surface of aspherical head of an intraluminal probes. The probes are dimensioned forvulval, cervical, endometrial, bladder, gastrointestinal, oral, nasal,aural and/or bronchial treatment.

[0079] In tests performed by the inventor, the efficacy of PDT using red(approximately 630 nm) emission from LED's was established in in-vivocomparative studies using a sub-cutaneous mammary tumour regrowth delayassay. Using radiobiological end-points, it was shown that thesolid-state prototype efficacies were comparable to that of expensiveconventional lasers for PDT (i.e. no significant difference, p=0.21).These results were confirmed in further clinical studies in thetreatment of Bowen's disease and basal cell carcinomas where comparativecomplete response rates were achieved as compared to laser PDT.

[0080]FIG. 26 shows a more specific example of the nineteenthembodiment, consisting of rows of blue LED's L_(B) interspersed withrows of red LED's L_(R) so as to form a discrete LED array composed ofdifferent types of LED as described above. The blue LED's L_(B) areswitchable on and off together, independently of the red LED's L_(R)which are also switchable on and off together. In this way, red or blueillumination may be chosen according to the type of treatment andpenetration depth required.

[0081] The blue LED's have an emission spectrum substantially (forexample fill width half maximum bandwidth) in the range 370 to 450 nm,and preferably 400 to 430 nm. This range is particularly suitable forthe treatment of pre-cancerous conditions, in particular actinickeratoses.

[0082] The red LED's have an emission spectrum substantially (forexample full width half maximum bandwidth) in the range 620 to 700 nm.This range is particularly suitable for the treatment of non-melanoma,such as basal cell or squamous cell carcinoma, or mycosis fungoides.

1. A light source for therapy and/or diagnosis, comprising an array oflight-emitting diodes mounted on a flexible backing, the array includinglight-emitting diodes of a first type having a first emission spectrumand light-emitting diodes of a second type having a second emissionspectrum different from the first emission spectrum.
 2. A light sourceaccording to claim 1, wherein said light-emitting diodes of the firsttype are independently switchable from said light-emitting diodes of thefirst type.
 3. A light source according to claim 1 or 2, wherein saidfirst emission spectrum is substantially in the range 370 to 450 nm. 4.A light source according to claim 3, wherein said first emissionspectrum is substantially in the range 400 to 430 nm.
 5. A light sourceaccording to any preceding claim, wherein said second emission spectrumis substantially in the range 620 to 700 nm.
 6. Use of a light sourceaccording to any preceding claim, in the treatment of a pre-cancerouscondition.
 7. Use according to claim 6, wherein said pre-cancerouscondition is an actinic keratosis.
 8. Use of a light source according toany one of claims 1 to 5, for the treatment of a non-melanoma.
 9. Useaccording to claim 8, wherein said non-melanoma is a basal cell orsquamous cell carcinoma.
 10. A light source for therapy and/ordiagnosis, comprising a non-planar array of discrete light-emittingdiodes mounted on a head portion for attachment to the head of a patientsuch that light is emitted onto the face of the patient.
 11. A lightsource for therapy and/or diagnosis, comprising a first rigid array oflight-emitting diodes, a second rigid array of light emitting diodesmovably connected to an edge of the first array and a third rigid arrayof light-emitting diodes movably connected to another edge of the firstarray.
 12. A light source as claimed in claim 11, further including afourth array of light-emitting diodes movably to a further edge of thefirst array.
 13. A light source as claimed in claim 11 or 12, arrangedfor treatment of the face and/or scalp.
 14. A light source for therapyand/or diagnosis, comprising a support for supporting the patient and anarray of light-emitting diodes mounted on the curved inner surface of arigid cover arranged to cover at least part of the length of a patientwhen supported by the support.
 15. A light source as claimed in claim14, wherein said support includes a further array of light-emittingdiodes.
 16. A light source as claimed in claim 15, wherein said furtherarray comprises a plurality of sections which are independentlyswitchable.
 17. A light source as claimed in any one of claims 14 to 16,wherein said further array is planar.
 18. A light source for therapy ordiagnosis of a patient, comprising an array of light-emitting diodesarranged within a housing, and an aperture allowing a part of thepatient's body to be inserted into the housing, the array being arrangedto direct light onto the part of the patient's body when inserted intothe housing.
 19. A light source as claimed in claim 18, wherein theaperture and housing are dimensioned to allow one or both elbows of thepatient to be inserted into the housing.
 20. A light source for therapyor diagnosis of a patient, comprising a plurality of independentlyswitchable co-planar arrays of light-emitting diodes.
 21. A light sourcefor therapy or diagnosis of a patient, comprising a housing in the formof a trapezoid prism open at the base and having an upper inner surfacecarrying an array of light-emitting diodes.
 22. A light source asclaimed in claim 21, wherein at least one of the inner side faces isreflective.
 23. A light source as claimed in claim 21, wherein at leastone of the inner side faces carries a further array of light-emittingdiodes.
 24. A light source for therapy or diagnosis of a patient,comprising an intraluminal probe carrying on a surface thereof an arrayof discrete light-emitting diodes.
 25. A light source as claimed inclaim 24, wherein said surface is substantially cylindrical.
 26. A lightsource as claimed in claim 24, wherein said surface is substantiallyspherical.
 27. A therapeutic light source, comprising an array oflight-emitting diodes arranged so that light from the light-emittingdiodes is incident directly on the treatment field with an intensity ofat least approximately 10 mW/cm², and means for cooling the diodes byforced air convection.
 28. A therapeutic light source, comprising anarray of discrete light-emitting diodes arranged to give an outputintensity of at least approximately 10 mW/cm², and means for cooling thediodes by forced air convection.
 29. A light source as claimed in claim27 or 28, arranged so that light from the light-emitting diodes has aspatial intensity fluctuation of approximately 10% or less in thetreatment field.
 30. A light source as claimed in any preceding claim,wherein the diodes are thermally coupled to one or more heatsinks.
 31. Alight source as claimed in claim 27, wherein the diodes are mounted atthe distal end of a passage for carrying the air from the proximal tothe distal end.
 32. A light source as claimed in claim 31, including afan mounted at the proximal end of the passage.
 33. A light source asclaimed in claim 31 or claim 32, wherein the distal end is dimensionedso as to be locatable proximate a cervix such that light from the diodearray is incident on the cervix.
 34. A light source as claimed in claim33, wherein the distal end is concave so as to fit over the cervix. 35.A therapeutic light source, comprising an array of discrete lightemitting diodes coupled to a tapered light guide arranged to concentratelight emitted by the light-emitting diodes.
 36. A light source accordingto claim 35, including a parallel-sided light guide coupled to thetapered light guide so that the light emitted by the light-emittingdiodes is concentrated into the parallel-sided light guide.
 37. Atherapeutic light source, comprising an integrated array of lightemitting diodes coupled directly to a parallel-sided light guide.
 38. Alight source as claimed in claim 37, wherein the diodes are thermallycoupled to thermoelectric cooling means.
 39. A light source as claimedin claim 35 or 37, wherein the parallel-sided light guide comprises oneor more optical fibres and/or liquid light guides.
 40. A therapeuticlight source comprising an array of light emitting diodes havingemission wavelengths substantially within the range 550 to 660 nm.
 41. Alight source as claimed in claim 40, wherein the emission wavelengthsare substantially within the range 590 to 640 nm.
 42. A light source asclaimed in claim 41, wherein the diodes are of aluminium indium galliumphosphide/gallium phosphide die material.
 43. A light source as claimedin claim 42, wherein the emission wavelengths are substantially withinthe range 560 to 644 nm.
 44. A light source as claimed in claim 43,wherein the diodes are of aluminium indium gallium phosphide/galliumarsenic die material.
 45. A light source as claimed in claim 42, whereinthe emission wavelengths are substantially within the range 650 to 660nm.
 46. A light source as claimed in claim 45, wherein the diodes are ofaluminium gallium arsenic die material.
 47. A light source as claimed inclaim 42, wherein the emission wavelengths are substantially within therange 550 to 570 nm.
 48. A light source as claimed in claim 47, whereinthe diodes are of gallium phosphide die material.
 49. A therapeuticlight source comprising an array of LED's with peak emission spectra ofapproximately 470 nm, 505 nm or 525 nm.
 50. A light source as claimed inclaim 49, wherein the diodes are of indium gallium nitride die material.51. A therapeutic light source comprising an array of LED's with peakemission spectra of approximately 430 nm.
 52. A light source as claimedin claim 51, wherein the diodes are of gallium nitride/silicon diematerial.
 53. A light source as claimed in any preceding claim, whereinsaid LED's include a first set of LED's and a second set of LED's havingdifferent emission spectra from said first set.
 54. A light source asclaimed in any one of claims 27 to 36 and 40 to 52, or claim 53 whendependent thereon, wherein the array is mounted on a flexible circuitboard.
 55. A therapeutic light source, comprising an LED array includinga first set of LED's and an independently switchable second set of LED'shaving different emission spectra from said first set.
 56. A lightsource for therapy or diagnosis, comprising an LED array including afirst set of LED's and a second, spatially distinct set of LED'sindependently switchable from said first set.
 57. Use of a light sourceas claimed in any preceding claim, for cosmetic treatment of a patient.58. Use as claimed in claim 57, for photodynamic treatment of thepatient.
 59. Use as claimed in claim 58, for portwine stain removal, orhair restoration or removal.
 60. Use as claimed in claim 57, for skinrejuvenation, wrinkle removal or biostimulation.
 61. Use of a lightsource as claimed in any one of claims 1 to 56, for medical treatment ofa patient.
 62. Use as claimed in claim 61, for photodynamic treatment ofa patient.
 63. Use as claimed in claim 62, in the treatment of one ormore of actinic/solar keratoses, Bowen's disease, superficial basal cellcarcinoma, squamous cell carcinoma, intraepithelial carcinoma, mycosisfungoides, T-cell lymphoma, acne and seborrhoea, eczema, psoriasis,nevus sebaceous, gastrointestinal conditions (e.g. Barratt's oesophagusand colorectal carcinomas), gynaecological disorders (e.g. VIN, CIN andexcessive uterine bleeding), oral cancers (e.g. pre-malignant ordyplastic lesions and squamous cell carcinomas), viral infections suchas herpes simplex, molluscum contagiosum, and warts (recalcitrant,verruca vulgaris or verruca plantaris), alopecia areata, or hirsutism.64. A light source for therapy or diagnosis substantially as hereindescribed with reference to and/or as shown in FIGS. 1 to 4, or FIG. 5,or FIG. 6, or FIG. 7, or FIG. 8, or FIG. 9, or FIGS. 10a and 10 b, orFIGS. 11a to 11 c, or FIG. 12, or FIG. 13, or FIG. 14, or FIG. 15, orFIGS. 16a and 16 b, or FIGS. 17a and 17 b, or FIGS. 18a and 18 b, orFIGS. 19a and 19 b, or FIGS. 20a and 20 b, or FIG. 21, or FIGS. 22a to22 c, or FIGS. 23a to 23 c, or FIG. 24, or FIG. 25, or FIG. 26 of theaccompanying drawings.